HUST 1010-The Minimum Length-KMP

[align=center]The Minimum Length[/align]
Time Limit:1000MS    Memory Limit:131072KB    64bit IO Format:%lld
& %llu
SubmitStatus

Description
There is a string A. The length of A is less than 1,000,000. I rewrite it again and again. Then I got a new string: AAAAAA...... Now I cut it from two different position and get a new string B. Then, give you the string B, can you tell me
the length of the shortest possible string A. For example, A="abcdefg". I got abcdefgabcdefgabcdefgabcdefg.... Then I cut the red part: efgabcdefgabcde as string B. From B, you should find out the shortest A.

Input
Multiply Test Cases. For each line there is a string B which contains only lowercase and uppercase charactors. The length of B is no more than 1,000,000.

Output
For each line, output an integer, as described above.

Sample Input

bcabcab
efgabcdefgabcde

Sample Output

3
7

有一个字符串，长度小于1000000。我一遍又一遍的重写。然后我有了一个新的字符串：aaaaaa ......现在我把它从两个不同的位置，得到一个新的字符串，然后，给你的字符串B，你能告诉我，例如最短的字符串的长度，A="abcdefg". I got abcdefgabcdefgabcdefgabcdefg....…然后我把红色部分：efgabcdefgabcde作为字符串B，你应该找出最短的A.

多试验例。每一行有一个字符串B只包含小写和大写。长度不超过1000000。

#include <cstdio>
#include <cstring>
#include <iostream>
using namespace std;
const int maxt=1000000+10;
char t[maxt];
int next[maxt];
int main()
{
while(scanf("%s",t)!=EOF)
{
int p=0,cur,l;
next[0]=-1;
next[1]=0;
l=strlen(t);
for(cur=2; cur<=l; ++cur)
{
while(p>=0&&t[p]!=t[cur-1])
p=next[p];
next[cur]=++p;
}
printf("%d\n",l-next[l]);
}
return 0;
}

KMP模板题，调用求子模板串的模式值next
，再用串的长度减去next
即得到答案。